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Name the four mechanisms of intracellular communication?
- 1. Direct - Ions via gap junction
- 2. Paracrine - Paracrine factors via extracellular fluid
- 3. Endocrine - Hormones via blood circulatory system
- 4. Synaptic - Neurotransmitters across neural junctions
What is the direct mechanism of intercellular communication?
- By ions via gap junction.
- (sodium, potassium, calcium)
- Cells are touching, gap junction between them
What is the Paracrine mechanism of intercellular communication?
- By paracrine factors via the extracellular fluid.
- In the same vacinity, gaps between cells, swim back and forth.
What is the Endocrine mechanism of intercellular communication?
By hormones via the blood circulatory system.
Travels further communicating with organs across the body
What is the Synaptic mechanism of intercellular communication?
- By neurotransmitters across neural junctions
- (nervous system)
- Synaptic cleft
What are the six endocrine glands which produce hormones?
- Pituitary Gland
- Thyroid Gland
- Pineal Gland
- Suprarenal Gland
- Parathyroid Gland
- They are well defined structurally and funtionally
What are the endocrine tissues in organs which are capable of producing hormones?
- Adipose Tissue
- Found within organs. Produce hormones to help organ do its job.
What are hormones?
Secreted into the blood and transported to target cells
Target cells have specific receptors on them
What are the five classifications of hormones?
- 1. Steroids
- 2. Monoamines
- 3. Oligopeptides
- 4. Glycoproteins
- 5. Polypeptides
What is the chemical structure of steroids?
Lipids (fats) or cholesterol
ex. Vitamin D, sex hormones
What is the chemical structure of monoamines?
A single amino acid which is modified or repeated
What is the chemical structure or oligopeptides?
3-10 amino acids
ex. Oxytocin in the reporductive system
What is the chemical structure of glycoproteins?
ex. luteinizing hormone
What is the chemical structure of polypeptides?
Made from 14-199 amino acids
ex. insulin and glucagon
What is the cascade of hormone secretion?
- 1. stimulus
- 2. gland (with hormone)
- 3. hormone excretion
- 4. enters the blood stream
- 5. out to receptor of target cell
- 6. action of hormone is manifested
- ex. sugar - - - to - - - - insulin
Hormone receptors are protein molecules located on which three parts of the cell?
- 1. Membrane
- 2. Cytoplasm
- 3. Nucleus
Where do steroid hormones bind to?
- nuclear receptors
- Associated with DNA transcription
Where do thyroid hormones bind to?
- Cytoplasmic receptors
- on mitochondria and ribosomes
Where do "all other" hormones bind to?
Cell membrane receptors
They activate a second messenger system (need help getting inside)
Are "all other" hormones hydrophobic or hydrophilic?
Water soluable not fat soluable.
Attach to receptors in the plamsa membrane. Then the second-messenger activation happens.
Are steroid hormones hydrophilic or hydrophobic?
Fat soluable only
Explain the negative feedback system?
endocrine gland hormones reach optium value
inhibits secretion of hypothalamic and anterior pituitary hormones that stimulate the endocrine gland
Describe positive feedback system?
- response to an endocrine gland hormone
hormone reaches optimal level
increases secretions of the hormone that stimulated the response
Where is the hypothalamus?
Central area of the basal brain limbic system
What does the hypothalamus consist of?
A large number of nuclei that modify and control the body functions via the hypothalamic hormones.
work on the pituitary gland which is the master organ of endocrine system.
Name the seven hormones that work on the anterior pituitary gland?
- 1. Growth Hormone Releasing Hormone (GHRH)
- 2. Growth Hormone Inhibiting Hormone (GHIH)
- 3. Prolactin Releasing Hormone (PRH)
- 4. Prolactin Inhibiting Hormone (PIH) (Dopamine)
- 5. Corticotropin Releasing Hormone (CRH)
- 6. Gonadotropin Releasing Hormone (GnRH)
- 7. Thyrotropin Releasing Hormone (TRH)
Name the two Hypothalamic hormones produced by the hypothalamus in posterior pituitary gland?
- 1. Antidiuretic Hormone (ADH)
- 2. Oxytocin (OT)
What is the pituitary gland?
- A small gland that is connected to the hypothalamus by the infundibulum.
- It had two parts
- Anterior pituitary gland (Adenohypophysis)
- Posterior pituitary gland (Neurohypophysis)
What is the Posterior Pituitary Gland called?
What is the Anterior Pituitary Gland called?
What is the posterior pituitary gland derived from and what does it connect and how?
- Derived from the neural brain tissue
- Connects the hypothalamus to the posterior pituitary gland by the Hypothalamic Hypophuseal Tract axons
What is the anterior pituitary gland derived from and what does it connect and how?
- Derived from ectodermal tissue in the roof of the embryonic mouth
- Connects the hypothalamus to the anterior pituitary gland by the Hypothalamic Hypophyseal Portal System.
- Seperior hypophyseal artery brings blood into the capillary beds of the Adenohypophysis of Pituitary gland. Hypophyseal veins carry blood away.
Where is Oxytocin (OT) made, stored and secreted from?
- Oxytocin is made in the Hypothalamus
- Ocytocin is stored in the Posterior Pituitary Gland
- Oxytocin is secreted from the Posterior Pituitary Gland
What is the target tissue of Oxytocin (OT)?
Smooth muscle of the reproductive system in both males and females.
What does Oxytocin (OT) stimulate?
- Stimulates semen propelling during ejaculation
- Stimulates uterine contractions during labor
- Stimulates milk ejection during suckling
What is the abbreviation of Oxytocin?
What is the abbreviation of Antidiuretic Hormone?
What is the second name for Antidiuretic Hormone (ADH)?
Where is Antidiuretic Hormone (ADH) (Vasopressin) made, stored, and secreted?
- Made in the hypothalamus
- Stored in the Posterior Pituitary Gland
- Secreted from the Posterior Pituitary Gland
What are the targetr tissues for Antidiuretic Hormone (ADH) (Vasopressin)?
Target tissues are kidneys and blood vessels
What does Antidiuretic Hormone (ADH) (Vasopressin) do?
- Increases waterreabsorption in the kidneys to increase blood volume
- Causes vadoconstriction of blood vessels to increase blood pressure
What is the abbreviation of Human Growth Hormone?
- 190 Amino acids in humans
What controls the secretion of hGH?
Secretions are controlled by hypothalamic GHRH (Growth Hormone Releasing Hormone) and GHIH (Growth Hormone Inhibiting Hormone)
What are the target cells for hGH?
All cells especially skeletal and muscle tissue
What is stimulated by the hGH?
- Directly stimulates stem cell growth and differentiation
- Stimulates liver systhesis and release of somatomedins
- Somatomedins mediates growth hormone functions by stimulating stem cell growth and differentiation.
- Results in growth to adulthood and maintenance of skeleton and muscles in adulthood
What do somatomedins do?
Somatomedins mediates growth hormone functions by stem cell growth and differentiation
What are the three Human Growth Hormone (hGH) Imbalances?
- Pituitary Dwarfism
What is pituitary dwarfism is caused by?
hyposecretion (decreased secretion hGH) in children and adolescents
What is gigantism caused by?
hypersecretion (increased secretion of hGH) in infants and children
What is Acromegaly caused by?
- hypersecretion (increased secretion of hGH) in adults resulting in distorted facial bones and features.
- (flat bones and soft bones will continue to grow)
What is Thyroid Stimulating Hormones abbreviation?
What controlls the secretion of Thyroid Stimulating Hormone (TSH)?
Secretions controlled by hypothalamic TRH (thyroid releasing hormone)
What is the target tissue for TSH?
Targets the thyroid gland
What does TSH stimulate?
Secretions of the thyroid hormones
What are the abbreviation for Adrenocorticotropic Hormone?
What controlls the ACTH?
Secretions controlled by hypothalamic CRH (cortiotropic releasing hormone)
What is the target tissue of the ACTH?
Targets the Adrenal gland cortex
What does ACTH stimulate?
Stimulates secretions of the adrenal gland cortex hormones.
What is the abbreviation for Prolactin?
What controls the secretion of PRL?
Secretions controlled by hypothalamic PRH (Prolactin Releasing Hormone) and PIH (Prolactin Inhibiting Hormone)
What is the target tissue of PRL?
Targets mammary glands
What does PRL stimulate?
Stimulates milk systhesis in the mammary glands
What controls the secretion of gonadotropoins?
Secretions controlled by hypothalamic GnRH
What is the abbreviation for Follicle Stimulating Hormone?
What is the abbreviation for Luteinizing Hormone?
The Anterior Pituitary hormone secretion is stimulated by releasing hormones (RH's) from the hypothalamus through what?
Hypophyseal Portal System
The Anterior Pituitary hormone secretion is inhibited by releasing ihibiting hormones (IH's) from the hypothalamus through what?
Hypophyseal Portal System
Control of Anteroir Pituitary gland hormone secretion is controlled by which feedback system?
All controlled by negative and positive feedback systems
Where is the pineal gland located?
In the roof of the third ventricle of the brain.
What does the pineal gland contain?
- Pinealocytes that secrete melatonin
When in melatonin secretion the highest?
When in melatonin secretions the lowest?
During the day
What are the three functions of Melatonin?
- Timing of sexual maturity
- Circadian rhythm setting
What does melatinon deficiency due to children?
- Causes premature puberty in children
- (ages 4-5)
What does Melatonin protect against?
Protection in the CNS against damage by free radicals
What does melatonin do for the Circadian Rhythm Cycle?
- Increasaed melatonin secretion may cause Seasonal Affective Disorder (SAD) during winter.
- AKA Winter Depression
Where is the thryoid gland look like and located?
- Large butterfly-shaped gland in the neck below the voice box (larynx)
- It had two lobes connected by an isthmus
- made of follicles filled with a colloid (gel-like material)
What is the bridge connecting the two lobes of the thyroid?
What are the follicles of the thyroid filled with?
Colloid (gel-like material)
What protein is stored in the colloid of follicle?
Thyroid hormone systhesis is stimulated by what?
Hypothalamus secretes TRH to the Anterior Pituitary which secretes TSH to the Thyroid gland.
What are the 8 steps in Thyroid Hormone Synthesis?
- 1. Iodide trapping by folicular cells (from blood) and transported into follicular lumen.
- 2. Synthesis of thyroglobulin by follicular cells and transported into follicular lumen.
- 3. Oxidation of iodide to iodine in lumen by thyroid peroxidase enzyme
- 4. Iodination of tyrosine molecules in the thyroglobulin chain to form T1 and T2.
- 5. Coupling of T1 and T2 to make T3 or T4.
- 6. Pinocytotsis of thyroglobulin chain by the follicular cells and digestion by lysosomal enzymes to produce free T3 and T4.
- 7. Secretions of T3 (Triiodothyroanine) and T4 (Tetraiodothyronine/Thyroxine) into the blood.
- 8. Transport of T3 and T4 in blood in the free form or bound to thyroid-binding-globulin (TBG)
What do Parafollicular C cells produce?
What are the Thyroid Hormone function of T3 and T4?
- 1. Increase the Basal Metabolic Rate (BMR) of all cells
- 2. Increase ATP production in mitrochondria of all cells by areobic cell respiration.
- 3. Promote normal growth synergistically (in collaberation with) with growth hormone
What does Calcitonin do?
- Decreases blood calcium levels
- (produced by C-cells)
- (works with parathyroid hormone)
Name the 4 thyroid gland disorders?
- 1. Cretinism (thyroid dwarfism)
- 2. Endemic goiter
- 3. Hypothyroidism (in adults)
- 4. Hyperthyroidism (in adults)
What is Cretinism (thyroid dwarfism) and what does it cause?
- Hypothyroidism during fetal development or during early infancy.
- Causes sever forms of mental and physical retardation in the newborn child. (if left untreated life span of 2 years, if treated with in 4 months it is reversable)
- Retardation is reversable only if horminal replacement therapy is started during the first 4 months of the newborns life.
What is Endemic goiter and when does it occur?
- Hypothyroidism caused by iodine deficiency
- Insufficient dietary iodine to make T3 and T4
- Occurs mostly in arid, dry, desert inland regions
- Lack of negative feedback from T3 and T4 causes over stimulation and overgrowth of the thryoid gland by TRH and TSH
- goiter results (enlarged throid gland)
What is Hypothyroidism (in adults) and what are the symptoms?
- Caused by too little T3 and T4
- Symptoms are:
- Decreased Basal Metabolic Rate (cell energy)
- Decreased Body Temp
- Cold intolerance
- Weight gain
- Myxederma (fish skin, dry, scaley)
What is Hyperthyroidism (in adults) and what are the symptoms?
- Too much T3 and T4
- Grave's disease is the most common cause (autoimmune disorder)
- Increased Basal Metabolic Rate
- Increased Body Temp
- Heat intolerance (miserable in hot areas)
- Anxiety & irritability
- Weight loss
- Exophthalmia (exophthalmos) bulging eyeballs
What are the parathyroid glands?
Four small glands on the posterior surface of the thyroid gland
What cells do the parathyroid gland contain and what does that cell secrete?
Contains Principal cells that secrete Parathyroid Hormone
What does Parathyroid Hormone regulate?
Along with Calcitonin they regulate blood calcium levels
What does Calcitonin do?
- Decreases blood calcium by:
- Increasing calcium excretion by the kidneys (out of blood and into urine by kidneys)
- Increasing calcium deposition in the bones
What does the Parathyroid Hormone do?
- Increases blood calcium by:
- Increasing calcuim reabsorption by kidneys (from urine back into the blood)
- Releasing calcium from bones into blood
- Activating Vitamin D which increases calcium absorption from intestines into the blood
What is another name for the suprarenal glands?
- Adrenal Glands
- (located ontop of the kidneys)
- They have 3 zones
- Capsule, Cortex and Medulla
- Medulla is a gland all on its own producing different hormones.
Suprarenal Cortex Zona Glomerulosa, or the outer and 1st zone secretes what?
- Outer zone secreting mineralocorticoids.
- (Minerals - Sodium and Potassium)
What is the major Mineralocortocoid in the Zona Glomerulosa or 1st zone of the suprarenal cortex and what does it do?
- Aldosterone is the major mineralocorticoid
- Increases retention of sodium by kidneys (takes back from urine into blood)
- Increases excretion of potassium by kindeys (potassium from blood into urine)
- Increases water retention and blood volume (increased blood volume = increased blood pressure)
What regulates Aldosterone in the Zona Glomerulosa or 1st zone of the suprarenal cortex?
Aldosterone secretion is regulated b sodium and potassium levels in the blood
Suprarenal Cortex Zona Fasciculata or the middle zone and 2nd zone secretes what?
Middle zone secreting glucocorticoids
What is the major Glucocortiocoid in the Zona Faciculata or the 2nd zone of the suprarenal cortex and what does it do?
- Cortisol is the major glucocortiocoid
- Increases glucose and glycogen systhesis (cells make more glycogen/glucose)
- Incease fatty acids (glucose) & protein (glycogen) breaking
- Reduces inflammation and allergic rashes
What glands regulates the secretion Cortisol?
Hypothalmic CRH (cortiotropic releasing hormone) and Anterior Pituitary ACTH (adrenal corticotropic hormone)
Suprarenal Cortex Zona Reticularis or the inner zone or 3rd zone secretes what?
- Inner zone secreting androgens (male sex hormone)
- (5% of male hormones come from Zona Reticularis and 98% from testes)
What does the secretions of androgen do for the female body in the Zona Reticularis?
- Stimulates pubic hair growth in puberty
- promote muscle mass, formation of the blood cells and libido in females
What regulates androgen?
Hypothalamic CRH (cortiotropic releasing hormone) and anterior pituitary ACTH (adrenal cortioctropic hormone)
The two Suprarenal gland disorders are?
- Addison's desease
- Cushings disease
What is Addison's Disease?
- Suprarenal gland disorder
- Insufficient suprarenal cortex secretions
- Lack of energy
- weight loss
- inability to resist stress
- loss of sodium and water in urine
- John F. Kennedy had this disease
What is Cushing's Disease?
- Suprarenal gland disorder
- Excessive suprarenal cortex secretions
- muscle wasting due to breakdown of proteins
- spindly thin arms and legs
- body fat redistribution
- rounded face (moon face)
- Fatty hump between shoulders (buffalo hump)
- Large abdomen with hanging-down fat
- Virilization (facial hair) and musculinization (muscles) in females
What kind of tissue is the Suprarenal Medulla made of?
Develops from the same nervous tissue as the sympathetic nervous system
Where are the Chromaffin cells located?
- Suprarenal Medulla
- Chromaffin cells receive direct innervation from the sympathetic nervous system
What increases hormone secretion by the adrenal medulla?
The adrenal medulla hormones are exactly the same in structure and function as what?
- sympathetic nervous system neurotransmitters
- - their effects mimic those of the SNS
- - they cause fight or flight behavior
Catecholamines are the collective name for what?
Epinephrine and norepinephrine
Suprarenal hormones are a back-up system for what?
sympathetic nervous system
What do catecholamines target?
targets all body cells
Catecholamines fight or flight reactions are what?
- increased heart rate and strength
- increased blood flow to skeletal muscles, heart and brain
- increased dilation of airways
- increased fuel for energy
- increased blood pressure
Describe the pancreas.
- 5 inches long with a head, neck, body and tail
- most are exocrime cells producing digestive enzymes
- endocrine cells in pancreatic islets produce hormones
What is the other name for the pancreatic islets?
Islets of Langerhan
Name the 4 pancreatic islet hormones, their % and what they produce.
- alpha cells (20%) glucagon
- beta cells (70%) insulin
- delta cells (5%) somatostatin (brake controller for glucagon and insulin)
- F-cells (5%) pancreatic polypeptide (PP-cells)
What does insulin do?
- Insulin decreases blood glucose by:
- 1. Increasing uptake of glucose into cells (cells take glucose from blood)
- 2. Increasing synthesis of glycogen (storage form of glucose) in the liver for storage
- Insulin increases protein synthesis in cells
- Insulin increases fat synthesis in cells
What does glucagon do?
- Glucagon increases blood glucose by:
- 1. Increasing synthesis od glucose from amino acids in the liver (making new)
- 2. Increasing breakdown of liver glycogen into glucose (already stored)
- 3. Increasing the release of glucose from liver into blood
- Glucagon increases fat breakdown in adipose tissue to free fatty acids (Lypolysis)
What is high blood glucose after a meal called and what does it stimulate and inhibit?
- Fed State
- stimulates the secretion of insulin and inhibits the secretion of glucagon
What is low blood glucose between meals called and what does it secrete and inhibit?
- Fasting State
- stimulates the secretion of glucagon and inhibits the secretion of insulin.
What is Deabetes Mellitus?
A metabolic disorder that produce high glucose levels in the blood. (Hyperglycemia)
What causes Diabetes Mellitus?
- caused by genetic defects that
- 1. decrease insulin secretions
- 2. produce defective insulin
- 3. defective insulin receptors
What is the other names for Type 1 Diabetes Mellitus?
- Juvenile Diabetes
- Insulin-Dependent-Diabetes-Mellitus (IDDM)
What are the characteristics of Type 1 Diabetes Mellitus?
- Usually develop in people younger than 7 years of age
- Beta cells are destroyed by own immune system
- Insulin levels are low or absent
- Insulin injections are required for life
What are the other names for Type 2 Diabetes Mellitus?
- Adult Diabetes
- Non-Insulin-Dependent-Diabetes-Mellitus (NIDDM)
What are the characteristics of Type 2 Diabetes Mellitus?
- Most common type of Diabetes (90%)
- Mostly in people over 35 who are obese
- Insulin may still be secreted but the body cells are less sensitive to insulin actions due to blocking of the insulin receptors
- may be controlled by diet
- insulin injections may not be required (as long as beta cells are still alive)
What are the 3 signs of Diabetes Mellitus?
- the 3 P's
- Polyuria - excessove urination
- Polydypsia - excessive water drinking
- Polypahgia - excessive eating
What is the job of the intestinal endocrine tissue and what are the important hormones?
- Intestinal hormones coordinate activities of the digestive system
- Most important ones are Cholecystokinin (CCK), Gastrin and Secretin
What are the hormones of the Kidney's endocrine tissue and what do they do?
- Calcitriol - is the active form of vitamin D that increases calcium absorption from the intestine.
- Erythropoietin - stimulates RBC production
- Renin(enzyme)-Angiotensin-Aldosterone - system affect blood volume and blood pressure
What is the hormone that the heart endocrine tissue has and what does it do?
Natriuretic Peptide - increases sodium and water excretion by the kidneys to decrease the blood volume if the heart is struggling with too much blood
What is the hormone that the Thymus endocrine tissue secretes and what does it do?
Thymosins - promote development and maturation of the T-Lymphocytes
What does the hormone of the Gonad endocrine tissue secrete?
- Testosterone and Inhibin in testes
- Estrogen and Progesterone in ovaries
What is the hormone secreted by the adipose tissue and what does it do?
Leptin - suppress appetite
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